Bi-polar batteries are able to provide an increased discharge rate and a higher voltage potential between its external connectors than standard wound or prismatic batteries, and are therefore in high demand for certain applications. Conventional batteries have been manufactured as either a wound cell battery that has only two electrodes or a standard prismatic cell battery that has many plate sets in parallel. In both of these types, the electrolyte can be shared everywhere within the battery. The wound cell and prismatic cell structures suffer from high electrical resistances due to their electrical paths having to cross multiple connections and cover significantly long distances to cover the complete circuit from one cell to the next in a series arrangement.
Recently, bi-polar batteries have been developed to generally include a series of stacked bi-polar electrode units (BPUs), each BPU being provided with a positive active material electrode layer and a negative active material electrode layer coated on opposite sides of a current collector (see, for example, Fukuzawa et al. U.S. Patent Publication No. 2004/0161667 A1, published Aug. 19, 2004, which is hereby incorporated by reference herein in its entirety). Any two adjacent BPUs have an electrolyte layer therebetween for electrically isolating the current collectors of those two BPUs. The series configuration of a bi-polar battery causes the voltage potential to be different between current collectors. However, if the current collectors contacted each other or if the common electrolyte of any two adjacent BPUs is shared with any additional BPU, the voltage and energy of the battery would fade (i.e., discharge) quickly to zero.
Accordingly, it would be advantageous to be able to provide a bi-polar battery with improved sealing of electrolyte between adjacent BPUs.